The invention relates to a ferrite antenna, with at least one winding which is wound about a core made of ferrite material, as well as a process for producing and tuning such a ferrite antenna.
The invention further relates to a key-less activation and/or closure device for vehicles comprising an antenna which is arranged in the door grip and which includes a core of ferrite material with at least one winding.
It is known, in connection with inductive assembly components and, especially, inductive coils, to wind one or several windings directly onto a core formed of ferrite material. Such inductive assembly components are described, for example, in German Utility Design Patent Nos. 298 04 135.9 and 298 24 118.8. With respect to these thus-configured assembly components, a subsequent tuning to a desired frequency or inductive value is difficult and time-consuming.
For this reason, in connection with ferrite antennas, the winding is generally disposed on a coil carrier comprised of synthetic or plastic material and, for tuning to a desired frequency or inductive value, a ferrite core is inserted or threaded into the coil carrier which is itself, for example, conduit-shaped, the ferrite core being movable in the axial direction and being fixedly securable to the coil carrier after the tuning, via, for example, adhesive securement. A ferrite antenna of this type is described, for example, in German Utility Design Patent No. 200 00 874.9.
With respect to such ferrite antennas, however, it is difficult to configure such antennas with greater than a predetermined length or with less than a predetermined thickness. These limitations arise from the fact that the production of very small ferrite cores of large length is time-consuming and difficult and the fact that the thickness of the coil carrier must be taken into account when considering the total thickness of the building components.
In current day technology, and, especially, in the construction of motor vehicles, there is increasing demand for inductive assembly components and, especially, ferrite antennas, which ferrite antennas, due to installation reasons, should be as long and small as possible, whereby the ferrite antennas should nonetheless be tunable. Such ferrite antennas find use especially in connection with key-less actuation and/or closure devices for vehicles, whereby the ferrite antennas are disposed in door grips, in the interior, or in the bumper.
The invention provides a solution to the challenge of creating a ferrite antenna which is tunable but which can be, however, nonetheless configured as long and small. The production cost should be the lowest possible achievable cost.